John flam



J. FLAM.

PERCUSSION FUSE. APPLICATION FILED JAN. 2. 1919.

Patented July 26, 1921.

UNITED STATES PATENT OFFICE.

JOHN FLAM, 0F THEUNITED STATES ARMY, ASSIGNOR TO THE SECRETARY WAR OFTHE UNITED STATES OF AMERICA.

PERCUSSION-FUSE.

Specification of Letters Patent.

Patented July 26, 1921.

Application filed January 2, 1919. Serial No. 269,381.

(FILED UNDER THE ACT OF MARCH 3, 1883, 22 STAT. L 625.)

following is a specification.

The invention described herein may be used by the Government, or any ofits otlicers or employees in prosecution of work for the Government, orby any other person in the United States, without payment of any royaltythereon.

This invention relates to a useful improvement in percussion fuses andmore particularly to safety devices whereby the projectile can not beaccidentally or prematurely exploded.

One object of my invention is to obtain a maximum of simplicity andsturdiness of construction in a safety device that is positive in itsaction. By this means a material reduction in cost is obtained.

Another object of my invention is so to arrange the safety means thatbefore the shell encounters its objective there is a strong forceconstantly tending to separate the firing pin and primer, thus obtainingabsolute safety. 30

Another object of my invention is to provide a safety device that iscompact and en tirely inclosed within the shell.

My device may be applied to any of the well known types of shellsarranged either for immediate or delayed firing, to drop bombs releasedfrom airplanes, or to incencharacters refer to like parts throughout theviews, the front casing 11 of the shell carries an annular flange 12near the rear. An internally threaded socket 13 is provided attherearend of the front casing 11. The cap 14 1S. of general bowl-shapedconfiguration, and 1S provided at its edge with the externallycut-threads l5 engaging with the internally threaded socket 13 of thefront casing 11. Said end cap 14 carries a flange 16 having a smoothsurface. 17 parallel with the smooth surface 18 of the flange 12. Thesurfaces 17 and 18, and the thin peripheral area 19 form a narrow pocketwhen the end cap 14 1s tightly screwed 1n place, for a purpose to belater described. At the center of the end cap 14 is the circular boss20. The end cap 14 is also provided with a plurality of ribs 21, thetops of which are adapted to engage and support the sprung disk 22.

he sprung disk 22 carries at its center the firing pin 23 and weight 24.The weight 24 is guided in its forward movement by the edges of the ribs21, so that the firing pin is constrained to travel along the axis ofthe shell. The firing pin 23 has an integral collar 25 bearing againstthe front face of the dlsk 22, and a shank portion 26 extending throughan aperture in the weight 24. The

weight 24 and firing pin 23 are securely held to the dlSk 22 by means ofriveting the shank 26 into the countersink provided at the rear of theWeight 24. The weight 24 has a spherical portion 27 conforming to theshape of the sprung disk 22 when said disk is thrown to its reverseposition.

A primer 28 is arranged a short distance in front of the firing pin 23and is adapted to fire the shell when pierced by the firing pin 23. Thecharge 29 of the shell is held in place therein in any suitable fashion.The charge 29 and primer 28, as mentioned previously, may be arrangedfor immediate or delayed firing, or for incendiary effects.

The sprung disk 22 is so made that should it be straightened by a forceacting therein, any additional strain produced thereon, no matter howsmall, will violently throw the disk 22 over center and it will assumethe reversed position shown in dot and dash lines. The sprung disk 22 isinitiall placed under a slight strain when the end cap 14 is screwed inplace, and there is therefore a constant force acting a ainst the boss20 and the front surfaces 0 ribs 21.

to carry the disk The sprung disk 22- is made of sufficiently heavyspring steel so that any shock or ar incident to transportation or handlng, such as that due to dropping the. shell from a crane, will not besuiiicient to throw the disk over center. there is a tendency for theweight 2% and the tiring pin 23 to keep going in the direction that theshell is dropped, due to the inertia possessed thereby, but the kineticenergy of the weight 24 and its associated parts is destroyed before thestrain in the disk 2'3 is sutiicient to cause it to snap over center.After the shock is over, the disk 22 immediatelyassumes the normalposition shown in Fig. 1. It is evident from this explanation that adistinct advantage is gained by this construction, in that no matter howoften the shocks may be repeated, the safety features cannot beimpaired. in function.

However, when the shell is actually fired a very large amount of kineticenergy 1s imparted to the weight 24.. The boss 20 and ribs .21 areprovided so as to furnish a large bearing surface for the disk 22. Thuswhen the shell is in the bore of the gun and subjected to a tremendousaccelerating force, the tendency for the disk 22 to be torn out of itspocket is overcome. lpon impact, the kinetic energy of the weight it issufficient over center. As soon as this occurs. the disk immediatelysnaps into the position shown in Fig. :2. and the firing pin 323 isviolently driven into the primer 2*. Thus all that is necessary is tostrain the sprung disk :22 sutliciently, and the construction of saiddisk itself will cause the proper movement of the tiring pin. The

actual tiring. therefore is not dependent directiy upon the impact ofthe shell, said impact being utilized merely to release a.

When such a shock occurs,-

strong force for producing the desired relative movement of the firingpin and primer. The force for piercing the primer is not reduced by anyspring arrangement that is so common with the ordinary type of fuse.

Since there is such a large difi'erence between the kinetic energyimparted to the weight Ziwhen it is dropped even from an appreciableheight, and when it is fired from a gun, no difficulty is experienced indesigning the disk 22 so as to insure firing the shell when it reachesits objective. The entire device comprises. for all practical purposes,a solid rigid structure, capable of being safelyhandled, or evenrepeatedly dropped from an appreciable height.

It is to be distinctly understood that my device may, if desired, beused in conjunction with any other safety means, for preventingaccidental tiring of the shell. The form shown is only one embodiment ofmy invention, and it is of course possible to reverse the arrangementshown by keeping the firing pin stationary and having the primermovable. i

Having now described my inventiomwhat I claim as new and desire tosecure by Letters Patent is:

In combination with a casing containing an explosive charge, a primerfor igniting said charge, a cap secured to the casing and formingtherewith an annular groove, guide ribs formed on the interior of saidcap, a spring plate having its periphery situated in the annular'grooveand slidable therein, a firing pin secured to the plate and normallyheld thereby in spaced relation to the primer and a weight secured tothe firing pin for placing initial tension on the plate, said weightguided in its movement by the guiding ribs.

JOHN FLAM.

